A preliminary analysis of the intergeneric relationships of the frog family Leptodactylidae

Abstract

Thirty-seven characters of external morphology, myology, osteology, life history, and chromosome morphology are studied. For each character, the evolutionary directions of changes of states are inferred. This information is used to construct a phylogenetic hypothesis of the intergeneric relationships of the New World frog family Leptodactylidae. Five major groupings of leptodactylids are proposed: the telmatobines, ceratophrines, leptodactylines, grypiscines, and eleutherodactylines. Formal recognition of these groupings is delayed until more information becomes available which will likely modify the intra- and intergroup relationships. The phylogenetic analysis demonstrates that the five groups are robust units, however.Recognition of the five groups allows a reinterpretation of the historical zoogeography of the family. The family Leptodactylidae had its origins in the temperate beech forests of South America. The telmatobines represent a remnant of the original leptodactylid stock, which has remained in the beech forests. Two groups became adapted to drying conditions, the ceratophrines and leptodactylines. The grypiscines represent a forest-stream adaptational complex that centered in southeastern Brazil. The eleutherodactylines were probably derived from a grypiscine ancestor. Early attainment of direct development in the eleutherodactylines was a preadaptation which resulted in an explosive radiation of the Eleutherodactylus-complex, which is now represented by about 350 species which occupy diverse environmental situations.A leptodactylid-liopelmatid relationship is suggested, which has the advantages of an in situ evolution of the leptodactylids rather than a migration from North Temperate regions as previously proposed. An alternate leptodactylid-discoglossid relationship argument which was based in large part on tadpole evidence is countered by a consideration of the major functional adaptations of tadpoles.